1. Field of the Invention
The present invention relates to a data transfer method for wristop computers. The invention also relates to an apparatus for wristop computers.
2. Description of Background Art
According to the state of the art, wristop computers typically include a transmitter belt connected by a flexible belt to a person's body, and which today typically measures pulse. This measuring device equipped with electrodes transmits a measurement message by radio to a wristwatch-like wristop computer, in which at least part of the received signal is processed and shown on the display of the wristop computer.
Wristop computers can be used to measure not only pulse, but also blood pressure, speed, acceleration, distance, and directional data.
If there are several sportspeople close to each other using wristop computers, which typically happens in exercise sessions with instructors, or in mass training events, the receiver must identify the correct transmitter.
According to the prior art, two alternative methods are used to identify the correct transmitter. For instance, Finnish patent 96380 discloses an analog solution, in which the time between at least two identifier pulses is used as the identifier data, by means of which the receiver can select the correct transmission signal from a group of several transmission signals. Implemented using analog technology, this system has been known to lead to error states, if the distance between the identifier pulses of two devices has brought them too close to each other. As a result of interference, for example, it has then been possible for the signals of two transmitters to be mistaken for each other, at least at times.
On the other hand, in newer devices, digital signal transfer with digital identification codes has been used. Though digital data transfer is very reliable, it does, on the other hand, consume a great deal of power in transmitter devices, which are typically battery powered.